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spinqualitylabelsall models 1gwg, resolution 2.01Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

TRI-IODIDE DERIVATIVE OF APOFERRITIN

Overview

A series of experiments performed at Cu Kalpha wavelength on in-house, X-ray equipment are presented which investigate two possibilities for, enhancing the experimental phasing signal by means of (i) triiodide/iodide, soaks using KI/I(2) and (ii) combinations of counter-ions introduced using, the short cryosoak method. Triiodide-derivative crystal structures for, five test proteins have been refined and reveal that iodine can bind as, polyiodide and single iodide ions through hydrophobic and hydrogen-bonding, interactions both at the molecular surface and in intramolecular and, intermolecular cavities. In three cases, the structures could be, automatically determined with autoSHARP using in-house SAD and SIRAS data., The investigation of combinatorial counter-ion replacement using multiple, salts with Na(+) and Cs(+) as cations and I(-) and Cl(-) as anions reveals, that, for the case of hen egg-white lysozyme, significant improvement in, phasing signal is obtained by the combined use of salts compared with, SIRAS methods using native and single short-soak derivative data sets.

About this Structure

1GWG is a Single protein structure of sequence from Equus caballus with IOD and CD as ligands. Structure known Active Site: CD1. Full crystallographic information is available from OCA.

Reference

Triiodide derivatization and combinatorial counter-ion replacement: two methods for enhancing phasing signal using laboratory Cu Kalpha X-ray equipment., Evans G, Bricogne G, Acta Crystallogr D Biol Crystallogr. 2002 Jun;58(Pt 6 Pt 2):976-91. Epub, 2002 May 29. PMID:12037300

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